VFD using MCPWM

[bmakovecki]

I'm planing to make 3-phase variable frequency drive with esp32.

I would like to generate 3 high-side hardware PWM and inverted 3 low-side hardware PWM with inserted dead time to charge bootstrap capacitor.

I've been playing with MCPWM library on arduino IDE.

My questions are:

1. How can I produce inverted PWM signal with dead time between the top and bottom switches to avoid phase shortcut ?
2. How can I acheve frequency grater than 312K Hz ?
3. Is there a way to insert few short pulses at begining and end of each phase to limit current.
4. If i change duty cycle by 1% at high frequeny, duty cycle doesn't change smootly it jumps every 10%

If I can achieve something like this would be perfect:

VFD.jpg (40.76 KiB) Viewed 5854 times

Regards,
Boris Makovecki

[Lucas.Hutchinson]

I am not sure what the ESP32 pwm hardware supports,

But if it doesnt support dead time insertion etc, then going with a FET driver that has cross conduction (dead time) logic and a few other protection features might be a good path forward.

Something like this from ST(or any other manufacturer, this is just a part number that i remember) shoudl do the trick:
http://www.st.com/content/st_com/en/pro ... l6230.html

this only required 3 pwm signals, and it generates the complementary PWM outputs for you.